GB387589A - Improvements relating to the rectification of alcohol - Google Patents

Abstract

Concentrated alcohol free from fusel oil is obtained from dilute worts &c. by concentrating the alcohol in a high degree column in the upper portion of which an entraining liquid is fed which carries the alcohol to the top of the column but prevents the fusel oils from rising <PICT:0387589/III/1> through it, and withdrawing laterally from the column at a point near the top thereof a ternary mixture of entrainer, water, and alcohol free from impurities, another portion of the said azeotropic mixture being withdrawn at the top of the column together with the impurities of low boiling-point. The liquids used are the same as those used in the dehydration of alcohol by the azeotropic method. Worts preheated in a condenser 1 and vinasse heat exchanger 2 are led through a pipe 3 into a column A in which the alcohol is vaporized in the lower part 5. Gasolene of B.P. 100 DEG C. which forms with water and alcohol a mixture of minimum b.p. of 68,3 C. is fed to the plates 4 while the zone 7 is left free for the cocentration of the fusel oils. The fractions collecting at the upper part of the column are withdrawn through a pipe 8 and after cooling are separated in a vessel 9 into an upper layer rich in gasolene which is returned to the column through a pipe 19 and a lower hydro-alcoholic layer containing 12 per cent gasolene and free from fusel oil. This layer is fed to a finishing column 13 where it is distilled with the aid of an "uniter" liquid, e.g. a volatile liquid which causes the alcohol to pass into the upper layer when the products are decanted in the separator 14. Suitable liquids are methyl and ethyl acetates, benzene, iso-propyl oxide, &c. The upper alcoholic layer is returned to the column 13 while the lower aqueous layer is freed in a column 15 from entrainer which is returned into circulation through a pipe 16, the dilute alcohol being returned to the column A through a pipe 17. Concentrated pure alcohol is withdrawn through a pipe at the bottom of the column 13. The accumulation of entrainer liquid in the column 13 is removed by returning the extra liquid through a pipe 19 to the column A. The volatile impurities of the wort, e.g. carbonic acid, ammonia, acetaldehyde acetone, amines, and light esters accumulate at the top of the column A from which they are withdrawn, washed with water, and decanted in a separator 10. The upper layer rich in entrainer is returned to the column A while the lower is rectified in a subsidiary column to concentrate the head products, alcohol being returned to the column A.